Genus/species: Hydrangea macrophylla. 
Varietal denomination: xe2x80x98Bailmerxe2x80x99.
The present invention relates to a new and distinct cultivar of Hydrangea macrophylla and will be referred to hereafter by its cultivar name, xe2x80x98Bailmerxe2x80x99. xe2x80x98Bailmerxe2x80x99 represents a new Bigleaf Hydrangea, a deciduous shrub grown for landscape use and for use as a potted plant.
The inventor discovered the new cultivar, xe2x80x98Bailmerxe2x80x99, in a cultivated garden in St. Paul, Minn. in the summer of 1983. The inventor observed the new invention for a three year period and recognized that it was unique in that it bloomed dependably in a Zone 4 climate and consistently displayed deep green, disease-free foliage. The inventor rooted softwood cuttings and set up a trial block at a nursery in St. Paul, Minn. for further observation in 1986. In 1998, additional trials were initiated both in St. Paul, Minn. and in Athens, Ga. to fully identify the unique characteristics of xe2x80x98Bailmerxe2x80x99 as compared to existing cultivars of H. macrophylla.
It was discovered through ten years of trials, that the new cultivar had the ability to dependably initiate blooms on new growth and that plants grown from softwood cuttings initiate and develop blooms without a chilling requirement. The new cultivar can be kept in perpetual bloom until fall by the removal of old flowerheads. These characteristics are atypical for Hydrangea macrophylla. H. macrophylla cultivars typically bloom on buds formed the prior season on old wood and develop only after a period of chilling and the flower buds are often killed by the harsh winter conditions in Zone 4. The parental background of xe2x80x98Bailmerxe2x80x99 is unknown.
The extensive trials indicate that the combined characteristics identify xe2x80x98Bailmerxe2x80x99 as unique and unlike any other known cultivars of H. macrophylla known to the inventor and the experts consulted. In comparison, the cultivars xe2x80x98Nikko Bluexe2x80x99 (unpatented) and xe2x80x98Gxc3xa9nxc3xa9ral Vicomtesse de Vibrayaxe2x80x99 (unpatented) have flowers that are similar in color to xe2x80x98Bailmerxe2x80x99 and have better cold hardier than most, however, they do not bloom dependably on new wood.
Asexual reproduction of the new cultivar was first accomplished by softwood cuttings in St. Paul, Minn. in July of 1986 by the inventor. The characteristics of this cultivar have been determined to be stable and are reproduced true to type in successive generations.
The following traits have been repeatedly observed and represent the characteristics of the new cultivar. These attributes in combination distinguish xe2x80x98Bailmerxe2x80x99 from other varieties in commerce known to the inventor.
1. Blooms on new growth. Removal of spent blooms results in perpetual bloom from summer through fall.
2. Hardy in Zone 4.
3. Increased mildew resistance as compared to some cultivars; more resistance than xe2x80x98Nikko Bluexe2x80x99.
4. Inflorescence color is pink, in alkaline soils and in any soils where aluminum levels or uptake is limited and blue in acidic with sufficient aluminum. The intensity and hue of the blue color is highly variable depending on soil pH and aluminum levels.
5. The ability to set flower buds on new growth without a cold treatment.
6. Foliage is deep green.